<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script src="../dev/vendors/vue.js"></script>
    <div id="example">
        <p>Original message: "{{ message }}"</p>
        <p>Computed reversed message: "{{ reversedMessage() }}"</p>
    </div>
    <div id="demo">{{ fullName }}</div>
    <script>
        var vm = new Vue({
            el: '#example',
            data: {
                message: 'Hello'
            },
            // computed: {
            //     // a computed getter
            //     reversedMessage: function () {
            //     // `this` points to the vm instance
            //     return this.message.split('').reverse().join('')
            //     }
            // }
            // in component
            methods: {
                reversedMessage: function () {
                    return this.message.split('').reverse().join('')
                }
            }
        })
    </script>
    <script>
        // var vm2 = new Vue({
        //     el: '#demo',
        //     data: {
        //         firstName: 'Foo',
        //         lastName: 'Bar',
        //         fullName: 'Foo Bar'
        //     },
        //     watch: {
        //         firstName: function (val) {
        //         this.fullName = val + ' ' + this.lastName
        //         },
        //         lastName: function (val) {
        //         this.fullName = this.firstName + ' ' + val
        //         }
        //     }
        // })
        var vm2 = new Vue({
            el: '#demo',
            data: {
                firstName: 'Foo',
                lastName: 'Bar'
            },
            computed: {
                fullName: {
                    // getter
                    get: function () {
                    return this.firstName + ' ' + this.lastName
                    },
                    // setter
                    set: function (newValue) {
                    var names = newValue.split(' ')
                    this.firstName = names[0]
                    this.lastName = names[names.length - 1]
                    }
                }
            }
        })
    </script>
    <div id="watch-example">
        <p>
            Ask a yes/no question:
            <input v-model="question">
        </p>
        <p>{{ answer }}</p>
    </div>
    <!-- Since there is already a rich ecosystem of ajax libraries    -->
    <!-- and collections of general-purpose utility methods, Vue core -->
    <!-- is able to remain small by not reinventing them. This also   -->
    <!-- gives you the freedom to just use what you're familiar with. -->
    <script src="https://unpkg.com/axios@0.12.0/dist/axios.min.js"></script>
    <script src="https://unpkg.com/lodash@4.13.1/lodash.min.js"></script>
    <script>
        var watchExampleVM = new Vue({
            el: '#watch-example',
            data: {
                question: '',
                answer: 'I cannot give you an answer until you ask a question!'
            },
            watch: {
                // 如果 question 发生改变，这个函数就会运行
                question: function (newQuestion) {
                this.answer = 'Waiting for you to stop typing...'
                this.getAnswer()
                }
            },
            methods: {
                // _.debounce 是一个通过 lodash 限制操作频率的函数。
                // 在这个例子中，我们希望限制访问yesno.wtf/api的频率
                // ajax请求直到用户输入完毕才会发出
                // 学习更多关于 _.debounce function (and its cousin
                // _.throttle), 参考: https://lodash.com/docs#debounce
                getAnswer: _.debounce(
                    function () {
                        if (this.question.indexOf('?') === -1) {
                        this.answer = 'Questions usually contain a question mark. ;-)'
                        return
                        }
                        this.answer = 'Thinking...'
                        var vm = this
                        axios.get('https://yesno.wtf/api')
                        .then(function (response) {
                            vm.answer = _.capitalize(response.data.answer)
                        })
                        .catch(function (error) {
                            vm.answer = 'Error! Could not reach the API. ' + error
                        })
                    },
                    // 这是我们为用户停止输入等待的毫秒数
                    500
                )
            }
        })
    </script>
</body>
</html>